The present invention relates generally to imaging systems, and more particularly to extending the dynamic range of an imaging system, particularly fluorescence imaging systems.
U.S. Pat. No. 7,286,232 and Application publication No. 2009/0080194, both of which are hereby incorporated by reference, describe a laser-based fluorescence imaging system with an enhanced optical filtering technique and uniform laser illumination that enables it to achieve high sensitivity and high dynamic range. In order to further provide repeatable quantification with this technology for a wider range of applications, it is desirable to have an even wider dynamic range capability so that users do not have to guess what exposure to use for imaging a sample. Also, this design is capable of producing repeatable signal-to-noise performance and the relationship between laser power, filtering efficiency, and CCD exposure time is known by design. This makes it well-suited for the efficient implementation described below to extend its use to cover applications with varying dynamic ranges.
Blinton et al. (U.S. Pat. No. 6,496,309) describe an apparatus that uses lamp light sources, filter wheels, and a CCD camera with an extended dynamic range. As is established by U.S. Pat. No. 7,286,232, laser-based fluorescence imaging lends itself much more easily to enhanced spectral filtering techniques to suppress optical background, especially for wide-area imaging. This, in turn, translates to better sensitivity of detection with lasers, an important factor in achieving wide dynamic range extension. Blinton et al. use a scatter-gram algorithm approach to check for saturation, change exposure time, and iterate until the captured image is noise-dominated. This method is, however, inefficient in that it uses an un-predictable trial-and-error approach and is limited by the above described optical background noise and camera noise (dark, blooming, and radiation events.)
Therefore it is desirable to provide systems and methods that overcome the above and other problems.